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-rw-r--r--tools/lib/bpf/hashmap.h195
1 files changed, 195 insertions, 0 deletions
diff --git a/tools/lib/bpf/hashmap.h b/tools/lib/bpf/hashmap.h
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index 000000000..10a4c4cd1
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+++ b/tools/lib/bpf/hashmap.h
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+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Generic non-thread safe hash map implementation.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+#ifndef __LIBBPF_HASHMAP_H
+#define __LIBBPF_HASHMAP_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <limits.h>
+
+static inline size_t hash_bits(size_t h, int bits)
+{
+ /* shuffle bits and return requested number of upper bits */
+ if (bits == 0)
+ return 0;
+
+#if (__SIZEOF_SIZE_T__ == __SIZEOF_LONG_LONG__)
+ /* LP64 case */
+ return (h * 11400714819323198485llu) >> (__SIZEOF_LONG_LONG__ * 8 - bits);
+#elif (__SIZEOF_SIZE_T__ <= __SIZEOF_LONG__)
+ return (h * 2654435769lu) >> (__SIZEOF_LONG__ * 8 - bits);
+#else
+# error "Unsupported size_t size"
+#endif
+}
+
+/* generic C-string hashing function */
+static inline size_t str_hash(const char *s)
+{
+ size_t h = 0;
+
+ while (*s) {
+ h = h * 31 + *s;
+ s++;
+ }
+ return h;
+}
+
+typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
+typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
+
+struct hashmap_entry {
+ const void *key;
+ void *value;
+ struct hashmap_entry *next;
+};
+
+struct hashmap {
+ hashmap_hash_fn hash_fn;
+ hashmap_equal_fn equal_fn;
+ void *ctx;
+
+ struct hashmap_entry **buckets;
+ size_t cap;
+ size_t cap_bits;
+ size_t sz;
+};
+
+#define HASHMAP_INIT(hash_fn, equal_fn, ctx) { \
+ .hash_fn = (hash_fn), \
+ .equal_fn = (equal_fn), \
+ .ctx = (ctx), \
+ .buckets = NULL, \
+ .cap = 0, \
+ .cap_bits = 0, \
+ .sz = 0, \
+}
+
+void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
+ hashmap_equal_fn equal_fn, void *ctx);
+struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
+ hashmap_equal_fn equal_fn,
+ void *ctx);
+void hashmap__clear(struct hashmap *map);
+void hashmap__free(struct hashmap *map);
+
+size_t hashmap__size(const struct hashmap *map);
+size_t hashmap__capacity(const struct hashmap *map);
+
+/*
+ * Hashmap insertion strategy:
+ * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
+ * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
+ * update value;
+ * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
+ * nothing and return -ENOENT;
+ * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
+ * This turns hashmap into a multimap by allowing multiple values to be
+ * associated with the same key. Most useful read API for such hashmap is
+ * hashmap__for_each_key_entry() iteration. If hashmap__find() is still
+ * used, it will return last inserted key/value entry (first in a bucket
+ * chain).
+ */
+enum hashmap_insert_strategy {
+ HASHMAP_ADD,
+ HASHMAP_SET,
+ HASHMAP_UPDATE,
+ HASHMAP_APPEND,
+};
+
+/*
+ * hashmap__insert() adds key/value entry w/ various semantics, depending on
+ * provided strategy value. If a given key/value pair replaced already
+ * existing key/value pair, both old key and old value will be returned
+ * through old_key and old_value to allow calling code do proper memory
+ * management.
+ */
+int hashmap__insert(struct hashmap *map, const void *key, void *value,
+ enum hashmap_insert_strategy strategy,
+ const void **old_key, void **old_value);
+
+static inline int hashmap__add(struct hashmap *map,
+ const void *key, void *value)
+{
+ return hashmap__insert(map, key, value, HASHMAP_ADD, NULL, NULL);
+}
+
+static inline int hashmap__set(struct hashmap *map,
+ const void *key, void *value,
+ const void **old_key, void **old_value)
+{
+ return hashmap__insert(map, key, value, HASHMAP_SET,
+ old_key, old_value);
+}
+
+static inline int hashmap__update(struct hashmap *map,
+ const void *key, void *value,
+ const void **old_key, void **old_value)
+{
+ return hashmap__insert(map, key, value, HASHMAP_UPDATE,
+ old_key, old_value);
+}
+
+static inline int hashmap__append(struct hashmap *map,
+ const void *key, void *value)
+{
+ return hashmap__insert(map, key, value, HASHMAP_APPEND, NULL, NULL);
+}
+
+bool hashmap__delete(struct hashmap *map, const void *key,
+ const void **old_key, void **old_value);
+
+bool hashmap__find(const struct hashmap *map, const void *key, void **value);
+
+/*
+ * hashmap__for_each_entry - iterate over all entries in hashmap
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry(map, cur, bkt) \
+ for (bkt = 0; bkt < map->cap; bkt++) \
+ for (cur = map->buckets[bkt]; cur; cur = cur->next)
+
+/*
+ * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
+ * against removals
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @tmp: struct hashmap_entry * used as a temporary next cursor storage
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry_safe(map, cur, tmp, bkt) \
+ for (bkt = 0; bkt < map->cap; bkt++) \
+ for (cur = map->buckets[bkt]; \
+ cur && ({tmp = cur->next; true; }); \
+ cur = tmp)
+
+/*
+ * hashmap__for_each_key_entry - iterate over entries associated with given key
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @key: key to iterate entries for
+ */
+#define hashmap__for_each_key_entry(map, cur, _key) \
+ for (cur = map->buckets \
+ ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
+ : NULL; \
+ cur; \
+ cur = cur->next) \
+ if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \
+ for (cur = map->buckets \
+ ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
+ : NULL; \
+ cur && ({ tmp = cur->next; true; }); \
+ cur = tmp) \
+ if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#endif /* __LIBBPF_HASHMAP_H */